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Installed a 3hp copland semi-hermetic 3 phase compresssor.
Wired the compressor according to schematic. Unit is dropping temperature, but Will not pump-down. Shut-off liquid valve pressure on low side will not budge. it stays at 5psi,. De-energized liquid line solenoid same effect.
high side is 220 psi. Is it possible that the compressor is wired wrong..

It is possible that it is overcharged and the receiver and condenser coil is full. It is also possible that your liquid pump-down valve is leaking. It is also possible that you have a combination of by-passing liquid pump-down valve and receiver valve.

If it is a rebuilt semi, then it is possible that the rebuild is no good.

I don't think the compressor is wired wrong but the contactor/control wiring maybe. Is the low pressure control accurate and set properly using gauges? When changing a compressor always change your contactor or relay especially if it is 3ph. If you changed it could you have wired it incorrectly?

Originally posted by R12rules I have personally removed ALL my hoses valve core depressors. Maybe one or two hoses still have one.

I have no use for them.
I use those brass check valves which screw onto the ends of the hoses. That way I can recover the charge from the hi side into the lo side when I am getting off a system.

A lot of guys dont bledd off from hi to lo and lose that amount of refrigerant.

(just running my posts up)

I used to be like you. No use for core depressors. But I am in HVAC now, and those damn units do not come with access service valves, just schrader ports. I hate them. But I am like you. Still no depressors, I use the brass checks.

Definately not a compressor wiring issue. Close the suction service valve and see what she does. If it won't do a good vacumm with the suction service valve closed call the wholesale house and get another one.

did your knees...

Originally posted by refer dude 2479
. But I am in HVAC now, [/B]

refer dude 2479,why are you an HVAC guy after 25 y. of refrigeration.I am curious because I read somewhere that a jouney of thousand miles starts with a single step.And I am more into ref.Did your knees give in?

Re: did your knees...

Originally posted by altan

Originally posted by refer dude 2479
. But I am in HVAC now,

refer dude 2479,why are you an HVAC guy after 25 y. of refrigeration.I am curious because I read somewhere that a jouney of thousand miles starts with a single step.And I am more into ref.Did your knees give in? [/B]

I survived a ruptured disc operation in 1991 and went another 10 years but the hours and the physical nature of refrigeration were taking their toll. Also here in the Bay Area (San Francisco) a/c guys make more per hour. Sometimes I am sorry I changed though because a/c does not challenge your mind like refrig.